Water treatment describes those processes used to make water more acceptable for a desired end-use. These can include use as drinking water, industrial processes, medical and many other uses. The goal of all water treatment processes is to remove existing contaminants in the water, or reduce the concentration of such contaminants so the water becomes fit for its desired end-use. One such use can be returning water that has been used back into the natural environment without adverse ecological impact.
The processes that have been suggested for use in treating water for solids separation include physical processes such as settling and filtration, and chemical processes such as disinfection and coagulation.
Biological processes have also been employed in the treatment of water, and these processes may include, for example, aerated lagoons, activated sludge or slow sand filters.
Surface cleaning apparatus such as pressure washers are useful for cleaning a variety of objects. Such devices require a clean supply of water for proper operation, but create wastewater by entraining solids from the cleaned surface into the used source water. Although there are many types of pressure washing systems, a typical system utilizes an engine that powers a pump. The inlet side of the pump is connected to a low pressure water source such as a tank or a municipal water supply, while the high pressure side of the pump is connected to a high pressure hose and wand for controlling the flow of high pressure water generated by the pump. The high pressure water is directed at a surface to dislodge dirt, paint and the like, and the water is generally allowed to drain into the storm sewer.
Ultra-high pressure washers, supplying more than 25,000 P.S.I. are also known. These systems include a large engine, typically diesel, which operates a large multi-cylinder pump to generate high volumes of water at ultra-high pressures. The ultra-high pressure water is directed through piping and/or hoses to various types of blast heads suitable for controlling the flow and direction of the ultra-high pressure water. One particular use for ultra-high pressure water devices is the removal of stripes or other markings from road surfaces. When polymers such as paint or plastic are used for roadway marking, the surface of the pavement is penetrated from ⅛-⅜ inch; whereby water blasting is the only known method of removing the stripe material from below the surface without removing a portion of the roadway surface. Ultra-high pressure water washers are also utilized for removing paint from ships, cleaning industrial facilities, removing graffiti, removing rubber from aircraft runways and demolition.
One problem associated with both low and ultra-high pressure water cleaning equipment is maintaining an adequate supply of clean water for continuous operation of the system. Dirty or contaminated water causes numerous problems with water cleaning equipment such as excessive pump wear, clogged filters, nozzles, screens and the like. Because cleaning often needs to take place away from municipal water supplies, water is often transported to the cleaning site. Because the water cleaning equipment requires large volumes of water to be effective, additional equipment is needed to haul in tanks of water. Alternatively, cleaning must be stopped so that additional water may be obtained.
Recovery and disposal of the water is another problem facing water cleaning equipment users. Demolition or even the mere cleaning of surfaces results in the water becoming contaminated with dirt and debris. This problem is particularly exacerbated with ultra high pressure water cleaning equipment which breaks dirt and debris up into particles small enough to remain suspended within the water indefinitely. Therefore, the contaminated water should be properly recovered and thereafter cleaned or contained before it can be disposed of.
Industrial systems that utilize filter belts are also known to be used for solid/liquid separation processes, particularly the dewatering of sludges in the chemical industry, mining and water treatment. The process of filtration is primarily obtained by passing a pair of filtering cloths and belts through a system of rollers. The feed sludge to be dewatered is introduced from a hopper between two filter cloths (supported by perforated belts) which pass through a convoluted arrangement of rollers. As the belts are fed through the rollers, water is squeezed out of the sludge. When the belts pass through the final pair of rollers in the process, the filter cloths are separated and the filter cake is scraped off into a suitable container. Water sprays are typically utilized to clean the filter cloth before it is reused. The water spray is reclaimed to be reprocessed or diverted to a drain for disposal. However, in these systems it is typically the solid filter cake that the user is interested in recovering and not the water that was carrying the solid particles, and thus the water typically remains dirty and is discarded to the drain.
Therefore, there is a need in the art for a water recirculation system that is suitable for applications such as high pressure or ultra-high pressure water cleaning equipment. The water recirculation system should provide a predetermined amount of clean water to start the cleaning operation. The water recirculation system should recover the dirty and contaminated water expelled during the cleaning process for removal of dirt and debris so that the water can be recirculated through the pressure cleaning equipment. The water recirculation system should be efficient enough to recirculate a sufficient volume of water for continuous operation of the water cleaning system. The water recirculation system should retain the dirt and debris for proper disposal. The water recirculation system should be compact enough to fit on a mobile frame that may also contain the high or ultra-high pressure water cleaning equipment.
There is also a need in the art for a water filtration system that is suitable for municipal, industrial and private uses. The water filtration system should utilize a continuous filter belt in combination with a settling tank for water containing a coagulant. The filter belt should be submerged within the settling tank a predetermined distance to control the hydrostatic head pressure utilized to push the debris containing water through the filter belt to limit the adhesion of the particles to the filter belt so that vacuum can be utilized to clean the filter belt for continuous use. The filter belt should be sized and the head pressure selected to provide a desired volume of cleaned water. The water can then be used as is or supplied to additional equipment or processes for further cleaning.
Thus, the present invention provides a water recirculation system for stationary or mobile applications and is particularly suited for surface cleaning apparatus and the like which overcomes the disadvantages of the prior art systems.